Driver rocket



Aug. 22, 1950 c. AN. HlcKMAN DRIVER ROCKET 2 Sheets-Sheet 2 Filed May17. 1945 .Fig-5., 7; //0 /Z q Q wwf, W

M MSW W 5W M Patentecl ug. 22, 1950 UNITED STATES PATENT O-FFECE DRIVERROCKET Clarence N. Hickman, Jackson Heights, N. Y., assignor to theUnited States of America as represented by the Secretary of WarApplication May 1'?, 1945, Serial No. 594,241

14 Claims. 1

The invention described herein may be manufactured and used by or forthe Government, for governmental purposes, without the payment to me ofany royalty thereon.

This invention relates, generally, to rocket apparatus, and morespecically to driver rockets for muzzle-loaded ordnance.

In muzzle-loaded ordnance, such as the 4.2" chemical mortar (pages 372through 378, Chemicals in War, by Prentiss, 1937, McGraw-Hill BookCompany, Inc.) the force of gravity is used to move the loadedprojectile or shell from the muzzle down the mortar tube or barrel intothe firing position. A fixed firing pin at the tube cap end or base ofthe mortar, res the propellant as soon as the projectile slides backinto the firing position against the firing pin. This method of loadingand firing is satisfactory forhigh-angle nre of the chemical mortar, butis impossible for low-angle re at point blank l ranges, because ofinsufficient gravitational force to move the projectile into lthe ringposition. That is, the mortar barrel .must be elevated to at least acertain minimum angle in order for it to be operated.

The present invention covers the means which I have provided to permit amortar to be effectively red not only at low angles of elevation, buteven with the mortar barrel depressed below the horizontal. Brieflystated, my present invention resides in providing driver rockets ormortars which can be attached to the nose end of a mortar shell andwhich will develop suiiicient driving force to drive the shell backwardthrough the barrel into the firing position. Although the driver rocketsof this invention are found to be particularly useful in connection withloading and ring the chemical mortar at all angles of lire, it will beapparent that. there are numerous other applications to which suchdevices may be put.

Although the present invention has been particularly made for use withthe 4.2" chemical mortar, and will be described hereinafter inconnection therewith, it will be apparent that it has generalapplication to all types of muzzle loaded weapons.

The object of this invention, generally stated, is the provision ofmeans whereby a muzzle loaded mortar may be fired at low angles ofelevation,

and even at angles of depression below the horizontal.

More particularly, an important object of this invention is to provide adriver rocket or motor adapted to be attached to the nose end or nosefuse of a mortar shell for driving the shell rearwardly into a ringposition against the ring pin.

Another object of the invention is to provide such a driver rocket thatwill be automatically detached from the shell or projectile to which ithas applied a desired thrust in response to launching of the projectile.

Still another object of the invention is to provide such a driver rocketor motor having a firing mechanism and suitable safety device to preventpremature firing.

Other objects and advantages of the invention will be readily apparentfrom the following detailed description of the embodiments illustratedin the accompanying drawings, in which:

Figure l is a longitudinal, vertical, sectional View of one embodimentof the invention;

Figure 2 is a left end, elevational View of the driver rocket shown inFigure l;

Figure 3 is a longitudinal, vertical, sectional view of another form ofdriver rocket embodying my invention;

Figure 4 is an elevational view, partly in section, of still anotherform of driver rocket and the nose end or a shell to which the driverrocket may be attached;

Figure 5 is a longitudinal, vertical, sectional View of another driverrocket Iorming another embodiment of the invention;

Figure 6 is a vertical, sectional view of modied means for fastening thedriver rocket of Figure 5 to the nose of a projectile;

Figure 7 is a longitudinal, vertical, sectional view of another form ofrocket motor forming an embodiment of this invention;

Figure 8 is likewise a longitudinal, vertical, sectional view or' stillanother driver rocket embodying the present invention;

Figure 9 is a longitudinal, vertical, sectional view of still anotherform of driver rocket forming another embodiment of this invention, themotor housing being shown separated from the ignition head; and

Figure l0 is an enlarged perspective view of the nozzle member of Figure1.

Referring now particularly to Figures 1 and 2 of the drawings, a driverrocket is shown generally at 9 comprising a motor housing or casing l]provided with a nozzle ll threaded thereinto, and further provided witha iront plug or head I2 threaded into the motor housing I0 and having aprojecting flange I3. The plug or head I2 is apertured so as to receivea blank cartridge or primer i4 therein, as shown` The motor housing Illcontains a cylindrical powder grain I of a rocket-type propellant.

The propellant l5 may be o Russian powder, about M3 in external diameterand about 11/8 in length. The diameter of the throat of the nozzle IIshould be about 0.02 square inch. The inner end of the nozzle I I may beprovided with several radially arranged ridges Iii which serve as apowder trap supporting the grain I5 while the gaseous products ofcombustion pass to the nozzle between the ridges. The forward or leftend of the powder grain I5 is provided with a coating of black powderII, or the like, to assist in the ignition of the grain. Other powdersuch as H-4 (T-Z) may be used by` making vsuitable adjustment ofdimensions. l y

A supporting sleeve I8 has a reduced section surrounding a portion ofthe motor housing IU and an enlarged section also surrounding the leftend of the housing I0 and extending theren from'. A shoulder 2e' isprovided between the two sections of theV sleeve IS and serves to retaina compression spring I 9 in place in cooperation with the flange I3 ofthe plug I2. AnA internally threaded coupling 21 is slidably tted in theleft end of the sleeve It; and is secured` thereto by means of a shear.Wire or pin 22` passing through :both of these parts, a-s 'shown inFigure 2. Within the sleeve I3l and between the coupling 2l: and theplug I3", is provided a slida-ble plunger or piston 23 carrying a firingpin 2LH rhe skirt portion of the plunger 23 is provided with a pairofdiametric'ally opposed slots- 25 through which the shear pinA 22extends. In order toprovide for the safe ringof theY driver rocket il,apull bar 2S isl provided which` extends throughsuiftable slots inthesleeve lil positioned so that the bar 25 separates the plunger 23 fromthe blank` cartridge I4. The slots in the sleeve 88- aceoinrrloe datingthe pullbar 2e are made longer thanA the width of the pull bar 26 sothat it may shittin position axially of the driver unit il.. The pullbar 26 may be provided with a ring 2l at one end to which apull cord maybe secured.

The driver rocket 9, having been describedin detail, its mode ofoperation is as follows:v

The coupling ZI is screwed on to the frontor nose of a projectile. As itis screwed on, the end or the projecting stud or thread on theprojectile nose engages and pushes the member 23 furtherl into thesleei-fe le thereby pushing against the pull bar 2t which in turn movesthe head plug l2 to compress the spring I9. En Fig. 1, the driver unitparts are illustrated inthe com pressed or loaded position, although thenose Aof the projectile which supports the unit is not shown. Theprojectile with the driver 4unit screwed thereon is then loaded into themuzzle of a gun or mortar and the unit is ready for firing and to exertathrust to push the projectile from the muzzle back into the firingposition. T he driver rocket is operated by withdrawing the pull bar 29by hand. As the pullbar Zal is withdrawn, the spring I9 forces the motorhousing I0, nozzle El and the plug E3 toward the projectile until theiiring pin 2li engages therhead of the cartridge I@ thereby ring thecartridge. The ring of the cartridge I4 ignites the blacrlg powder il onthe end of the propellant grain I5 and thus ignites the propellant. Asthe grain I5 burns, the combustion gases escape from the motor housinglo through the nozzle I l' exerting' a thrust through the housing lo andthe plug t2 on the' meint-cr ze which being in' contact with the end ofthe projectile applies the thrust to the projectile to push itrearwardly through the gun barrel into the tiring position. When used inconnection with the chemical Warfare service mortar the movement of theprojectile to the ring position is such as to fire the propellant chargeby percussion as it seats in the ring position against the breech firingpin of the mortar. The charge I5 of thev driver' rocket burns in about0.2 second to eert' a driving thrust of about 40 pounds. When theprojectile propellant is ignited, the forward acceleration of theproject'ile is suflicient to shear the pin or wire 22 which releases thesleeve IB from coupling member ZI. VBy' providing a shear pin 22 thatwill shear at about al 20GV pound thrust, the pin is not sheared by the40 pound thrust of the driver rocket, but is" sheared by the 600 poundthrust of the accelerating projectile as it leaves the gun. After thepin i222 shears, and the accelerating motion of the projectile hasystopped, the compression of ther- 'spring le will eject the`V driverrocket unit from the path er' the projectile, leave lng the coupling'member 2l on the nose of the projectile. Y

Referring' new tcy the ccrlstmctlcnY shown ln Figure'S of the drawings,a' drivel" rocket is' ii'ld'ii' cated generally at 2&3' whichvl is iigenera-lA similar to the driver rocket of Figuresl and 2; The rocketmotor -i comprises 'a motor lflousii'lgv 3i), a nozzle 3l, a plug orhead 32, a propellant gr'a 'l Staand a rlr'ing' cartridge The plug' is`-c lindrical in shape and its rig/ht'v end is" threaded into the motorhousing 30; The blank" cartridge is seated in a central holev providedtherefor in the plug 32', arid is held this Seated posi: t'lon by atransverse wire ety extending through the plug 32; A firing' pin 3l,surrounded a compression spring' SS; is carriedvv'itl'ii'nI the'extended portion of the plug I coupling member 3Q is attac-hed to theplug' 322 by al shea-r wir-c er ein all, and the rlrlg sin ai is'Secured to the coupling member 39 by a' pullpin or hat el. 'rilecoupling efe is provided with' 'a threaded extension' or stem 32 adaptedtobe screwed into' the nose of a projectile so as to attach the drive'rrocket 29' thereto; A plurality ofV slidabl pins als extend in parallelthrough the coup .ng itember Se', and have headset adapted to enga-ge awasher i5 abutting the left end of the spring Sli.

when the diri-ver uil-lt ls attached toA the 'nece of a projectile, suchas a 12 mortar shell, by screwing the stud d'2 into the nose' tube, thenose' pushesA the pins" e3' throu-g'flik the coupling inem# ber 39" sothat theV ends'- 44 bear against the washer i5 and compress theSp'ring'ril. When is desired' to fire tilevl dr'lverrockcte'-, the pallpin `l I is withdrawn permitting the spring 38 to drive the pin 31against the bl'a r`4lfkY cartridge or priilfer se so' as tov set itch?,The primer sa eresV tue charge 35 withintifc motor housing Se whichburns to deliver the desired drive or thrust to" the projectile. A 'Ill' rrode oi' operation is thus similar to' that of the'coh'striice tionshown n Figures l and 2'. As the projectile accelerates lnforward'mcvementf on being ered from the mortar the' shear wire' fail"is* sl'iealed thereby releasing the main portion of the driver rocket19'k from' the coupling member S" so that the former' may' be pushed bythe sprl-rig 3S from theV path Aof the'- projectile.

Ihe modi-fled construction indicated generally at 49 in Figure 4, is inAgeneral like the con`stri-L tio-nsv previously described excepii'thatthe driver rocket body mem-ber es is prei/ille@ with radially extendingfinsV or varies Mp This construction Serves to automatically detach thedriver rocket 49 from the nose of a projectile 52 due to the rotation ofthe projectile as it is fired from a rifled barrel or tube. The vanesare of such area as to tend to prevent the driver rocket 49 fromrotating as fast as the projectile, thereby serving to unscrew thedriver rocket 49 from the threaded extension 53 or projectile nose. Thedriver rocket 49 includes a firing pin 54, a pull bar 55 and a firingpin spring 56. A retainer or plunger 51 is provided which slidably ntsover a stem extension of the firing pin 54, as shown, and serves tocompress the spring 56 when the driver rocket 49 is sc-rewed on to thethreaded end 53. Upon pulling the bar 55 the firing pin 541s releasedand serves to set off/the propellant in the motor section (not shown) ofthe driver rocket 49.

In Figure 5 of the drawings, a modied construction is shown includingmeans for detachably. securing a driver rocket 59 to the tapered nose 69of a projectile. The driver rocket 59 includes a motor 62 provided witha nozzle 63 and a powder trap 64. The forward or left end of the motorhousing 62 is closed by a plug 65 apertured to accommodate a blankcartridge 66. A sleeve 61 is threadedly secured to the left end of themotor housing 62 and is provided with a ring 68, as shown. The ring 68incloses a centrally threaded ring 69 having the same diameter as thesleeve 61, the ring 69 being screwed on to the threaded ring member 6|.Radially extending shear pins 19 serve to initially secure the sleeve 61to the ring 68 and to secure the ring 68 to the ring member 69.

Within the sleeve 61 and attached to the plug 65 by machine screws (notshown) is a plate 1|. The plate 1| holds the cartridge 66 in place andcarries a firing wedge 12 on a spring arm 13 in a position to be driventhrough an opening in the plate 1| so as to fire cartridge 66. The plate1| also supports a stem 14. Opposing washers or plungers 15 and 16,separated by a collar 11, are slidably mounted on the stem 14 and retaina compression spring 18 therebetween. A pull pin `19 extends through thesleeve 61 from side to side to prevent the washer 16 from contacting thefiring wedge 12 until it is desired to fire cartridge 66. A cylindricalgrain of rocket type propellant (not shown) is carried in the rocketmotor housing 62 as in the driver rocket 9 of Figure l.

The method of operation of the driver rocket 59 of Figure 5 will now bedescribed. The ring member 6| is secured to the nose 69 of a projectileby cement or the like. The driver rocket carrying rings 68 and 69 issecured to the ring member 6| by screwing thereon. As the ring 69 issecured to the ring member 6|, the end of the projectile nose 69 engagesand urges the washer 15 to the right along the stud 14 compressing thespring 18. The pull pin 19 abuts against the Washer 16 preventing thelatter from engaging the firing wedge 12. When it is desired to fire thedriver rocket, the pull pin 19 is manually withdrawn permitting thespring 18 to push the washer 16 into engagement with the ring wedge 12which latter then strikes the cartridge 66 to fire the same.` When thecartridge 66 is red, it ignites the rocket-type propellant in the motorchamber 62. The products of combustion from chamber 62 exhaust throughnozzle 63 creating a driving thrust to the left to drive the projectile69 into its firing position as explained hereinbefore. The drive thrustof the driver rocket is not sufficient to shear the pins 19. When theprojectile itself lires and moves to the right, its accelerating forceis suicient to shear the pins 19. The driver rocket 59 is then free tofall away from the projectile nose 69, and drops out of the path offlight of the projectile.

In Figure 6 of the drawings a modified construction is shown whereby thedriver rocket 59 of Figure 5 may be attached to the nose 69. Thismodiiied construction involves three rings 89, 8| and 82 connected byshear pins 83, as shown. The accelerating force is sufficient to shearthe pins 93.

In an effort to simplify and lighten the driver rocket constructionsdescribed above in connec- Y tion with Figures 1 through 6, the modifieddesign indicated generally at 99 in Figure 1 of the drawings wasdeveloped. The driver rocket 99 represents approximately fifty percentreduction in weight and also eliminates the hazard of nying rings whichexist in connection with driver rocket 59 of Figures 5 and 6. The driverrocket 99 comprises a rocket motor 9| having a nozzle 92 screwed intothe rear or right end thereof. The inner face of the nozzle 92 isprovided with radial ridges 93 which constitute a powder trap for thepowder grain (not shown) retained in the chamber of the motor 9|. Theforward or left end of the motor 9| is a thickened section 94 and has anL-shaped opening 95 formed therein. The short leg of the opening 95opens into the powder chamber while the long leg is tapped at its outerend so as to receive a firing pin holder 96. A blank cartridge 91 isheld in place by the plug 96.

In order to ignite or re the blank cartridge 91, a firing pin |99 isprovided which is slidably retained in the holder or plug 96. The firingpin |99 is adapted to be driven against the blank cartridge 91 by ahammer 9| carried on one end of a leaf spring |92. The leaf spring |92is secured at its opposite end to a projection |93 formed on a Washer|94. The washer |94 is retained in place between the motor housing 9|and the nozzle 92, as shown. The hammer |9| is held away from the firingpin |99 by means of a flange |95 formed on the head of a pin |96 whichextends crosswise through a hole provided therefor in the thickenedsection 94. A pull cord |91 with a pull |98 are provided for withdrawingthe pin |96.

In order to attach the driver rocket to the nose end or fuse of a mortarshell, an internally threaded ring ||9 is provided which is adapted tobe screwed on to the nose end or fuse. The ring |,|9 is secured to themotor 9| by means of two sets of pins III, ||2 which meet in anintermediate ring ||3 therebetween. Registering holes are provided inthe opposing ends of the thickened section 94 and the ring ||9 so as toreceive the ends of the pins and ||2. The recesses or holes for the pins||2 in the thickened end 94 are of such a depth that the pins ||2 canextend thereinto to about one-half the length thereof, while thereceiving holes in the ring 9 for the pins are of such a depth that theycan accommodate the full length of the pins However, in the initialassembly of the driver rocket 99 the pins abut against the ends of the-pins I2 and extend only about halfway into the holes provided thereforin the ring ||9, as shown in the drawings.

In operation, the driver rocket 99 is screwed on to the nose end or fuseof a mortar shell, and the shell is then positioned in the muzzle endconstruction, th driver ro'cietihdihatd genera-1: 1y at H5 Figr' S' ofthe drawings was pro*- vided. The driver rkt H5' onipriss a boy H5having a otd s'tih H? andl a somewhat ehlaigedl adaptor sotioh H8. AYnozzle |36 is screwed into the7 rear @nu of the 'rhotbr section H1 anda pw'cl'er grain mi semi-red thrih between a powder' trap' |22- form'ed'r' the inri'er face' 0f the I'OZZS" |23 aid 'VJSHr |31?. Th iihg pinarrangemeht for theA drive'i1 rocketv H5 is Similar to that oi thedriver rock-'et Se ih Fi'ga 7; That is, a' firingiin |'2 is carri'c i apiti |25 which aise' srves' to' retain blank cartridge |26 in its satedplstih.' Hfmier I2?- ('Zai'tfdA by a leaf spring |23' is v"""ovidd" toStrike -rihgpin IZ; The hammer l`2'Y is ribra'ily separated from the"rih'gl pin IZS by 'means 'of 'cup-'shaped stamping ,|29 c'rd on tifibili |39. The pin extends through a taii'sverse 11G-1e' providedtherefor iii the' adaptor se'ctio'n Si.

The' thickened the matar shells. th

tothe rear end of a motar tube or barrel to ignite thel same. A numberof driver rockets embodying "this invention have been made andsuccessively `tested with the 4.2 chemical mortar. Of course, `the sameprinciples would apply to any type of muzzle-loaded mortar.

Since certain further changes may be made in the foregoing constructionsand diiierent erni bodiments of the invention may be made withoutdeparting from the scope of the invention, it is intended that allmatter described heretofore or shown in the accompanying drawings beinterpreted as illustrative and not in a limiting sense.

I claim:

1. In combination, a mortar shell adapted to be red from amuzzle-loading mortar, and a driver rocket secured to the nose end ofsaid mortar shell, said driver rocket comprising a casing having aforwardly-opening nozzle, a charge of propellant in said casing incommunication with said nozzle, and means to ignite said propellant tothereby drive'said shell rearwardly.

2. A driver rocket device comprising in coi-u bination, a motor housingfor containing a pro pellant charge, a nozzle secured to one end of saidhousing, a head secured to the opposite end of said housing, said headhaving an aperture therein to receive a blank cartridge, a firing pincarried within said head, a spring in engagement with said pin, and acoupling element for'seuring said head to an object to be driven, saidspring being compressed in response to operation of said couplingelement to secure said head to the object to be driven.

3. A driver rocket device for use in driving a muzzle loaded ordnanceprojectile from the muzzle to the iiring position in a gun, comprising amotor housing for containing a propellant charge, a nozzle at one end ofsaid housing, a head at the opposite end of said housing, ignition meanscarried by said head for igniting said charge, coupling means detachablyconnected to said head and operable to fasten said device to the nose ofsaid projectile, and means responsive to operation of said fasteningmeans to arm said ignition means.

4. A driver rocket device comprising, in combination, a motor housing, adischarge nozzle secured at one end of said motor housing, means f forclosing the opposite end of said motor housing, an L-shaped openingprovided in said closed end with a leg opening into the motor housing,and the other leg opening to the side of said motor housing, a primersecured in said side leg of the opening, a ring pin, ring pin holdingmeans also in said side leg of the opening serving to retain said primerin place and to hold said firing pin in a position to strike thecartridge, a hammer for striking said ring pin, spring means for urgingsaid hammer to strike said iring pin, and ring means adapted to normallyseparate said hammer from said firing pin and manually withdrawable tosimultaneously bias said spring means and then release said hammer todetonate said primer.

5. The combination with a motar shell adapted to be red by translationrearwardly from muzzle to breech within the barrel of a mortar, saidshell having a nose, of a driver rocket comprising, a

cation with said nozzle, and means within, said casing to ignite saidcharge to thereby propel said rocket and shell rearwandly within themortar barrel.

6. The combination with a shell having a propelling charge ignited inresponse to rearward translation of said shell within a gun barrel fromthe muzzle thereof, of a driver rocket adapted to be attached to thenose of said shell and comprising a casing, a forwardly directed nozzleclosing the forward end of said casing, a propelling charge in saidcasing, percussion means operable to ignite said charge, a springadapted, when tensioned, to urge said percussion means intochargeeigniting movement, and means responsive to attachment of saidrocket to said shell, to tension said spring.

'7. A driver rocket comprising a casing, a nozzle secured to the forwardend of said casing and in communication with said casing, a propellantcharge in said casing, normally safe percussion firing means carried bysaid casing and operable to ignite said charge, means operable to attachsaid casing to the nose of a shell with said nozzle directly forwardly,and means responsive to operation of said attachment means to arm saidpercussion ring means.

8. In a driver rocket, a motor housing, a nozzle and a head secured toand closing respective ends of said housing, a propellant charge in saidhousing, a primer carried by said head for igniting said charge, afiring pin slidable in said head to detonate said primer, a spring insaid head and operable when stressed, to urge said firing pin intodetonating relation with said primer, screw means united with said headfor attaching said rocket to an object to be driven, and meansresponsive to turning of said screw means in attaching said rocket to anobject, to stress said spring.

9. A rocket as recited in claim 8, and a safety pin connecting saidfiring pin and screw means, said safety pin being withdrawable to freesaid firing pin to the action of said spring.

10. A rocket device as recited in claim 4, safety means normallyoperative to prevent Withdrawal of said firing means, and meansresponsive to attachment of said device to a mortar shell for drivingthe same, to render said safety means inoperative, whereby said ringmeans may be withdrawn.

11. In combination with a mortar shell adapted to be fired bytranslation rearwardly in and along a mortar barrel from the muzzlethereof, a driver rocket, a propelling charge in said rocket meansoperable to connect said rocket to the nose of said shell in position totranslate the same rearwardly, normally inoperable firing means forigniting said propelling charge, and means responsive to operation ofsaid connecting means in connecting said rocket to a shell, to rendersaid ring means manually operable.

12. In a driver rocket, a housing having a forwardly-directed nozzle atits forward end, a plug closing the rear end of said housing, a primermounted in an aperture in said plug in position to ignite a propellantcharge in said housing, a sleeve secured to said housing and extendingrearwardly therefrom, i'lrst and second washers reciprocably tting saidsleeve, a spring interposed between said washers, a firing pin carriedby said plug and adapted to detonate said primer on impact by said ilrstWasher, manually-withdrawable safety means normally preventingimpingement of said rst washer against said ring pin, and means operableto simultaneously attach said sleeve to the nose of a` shell and toforcesaid second washer toward said Washer to Ithereby stress saidspring and urge said first washer ,intodetonatlng impingelnentagainst.said

`firing pin.

13. .A driver roeketasleo-ted .in elam said attaching means comprisinga. -rst ring, .a Segond ring fitting over and about Said .irst Vfing andsaid sleeve, and radial shear pins .oo-nneotng said -frst and secondrings and Said Segond ring and sleeve.

14. A driver rocket device comprising, in .come ,bination a motorhousing, a propelling .Charge in said housing, .a discharge nozzle@losing one end of said motorV housing, plug means oloeing the oppositeend of Said motor housing, a primer mounted said nlug means and adaptedto .re said propelling charge, a ring pin mounted in a stellung positionrelative 4to said primer and .mally biased .away therefrom, an ignter.easing Soeurod to Seid motor housing .at the end one posit@ saidnozzle, plunger means disposed Within said .casing and adapted to strike,s aicl ming pin 12 l to detonate vSaid primer, normally -unstressedSpring means iin Seid easing and ,Stressalole to urge said plunger intoring movement, remgv.-

able safety means normally preventing said plu-nger Ineens from engaging.Seid ring ein,

means for coupling said driver-rooket-to the front,

end of a mortar shell, and means responsive to operation of saidcoupling means in connecting said device to a shell, to stress saidspring means,

CLARENCE N. HICKMAN,

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS

